By far the greatest number of people lived in the Mesa Central. Most were under the general rule of the Aztec Empire, but a great many separate cultural groups thrived in the region, among them speakers of Tarastec, Otomi, and Nahuatl. Outside the Mesa Central were numerous other cultural groups such as the Maya of the Yucatan and the Mixtecs and Zapotecs of Oaxaca. Highly organized civilizations had occupied various regions of Mexico for at least 2,000 years prior to European discovery. The Aztec cities of the Mesa Central were marvels of architectural design, irrigation technology, and social organization. Spectacular Mayan ruins in the Yucatan evidence widespread urbanization and intense agricultural productivity dating from well before the Christian Era.

Over the last four centuries descendants of Indians and Europeans, sometimes called mestizos, have become the dominant group in Mexico. Today they account for at least two thirds and perhaps three fourths of the total population.
Source: www.hispanomundo.com/Mexico.htm